Kane Williamson was reported following New Zealand's 10-wicket defeat in the second test to the West Indies in Trinidad, the ICC said in a statement.

New Zealand part-time spinner Kane Williamson has been reported for a suspected illegal bowling action and ordered by the International Cricket Council to undergo official scrutiny within 21 days.

Williamson was reported following New Zealand's 10-wicket defeat in the second test to the West Indies in Trinidad, the ICC said in a statement on Sunday.

Match referee Chris Broad has handed New Zealand officials a copy of the umpires' report citing concerns over a number of deliveries they considered to be suspect, and saying they believed that his action needed to be tested.

Under cricket's rules, a bowler is allowed no more than 15 degrees of flex in the elbow during delivery.

"Whether he's close to the 15 degree mark, that seems to be the criteria," New Zealand coach Mike Hesson said.

"So if he's less than that then he'll be passed fit to carry on as per normal. If not then there'll need to be some remedial action take place."

Hesson said he was not overly surprised his occasional off-spinner had been reported as the ICC clamps down on illegal deliveries.

"I don't think it's been completely unexpected and in all honesty we're fully supportive of going through the process," he told Radio Sport.